Some hydraulic control systems employ a regeneration circuit to fill the expanding side of a hydraulic motor with fluid exhausted from the contracting side of the motor. Thus, less fluid is required from the system pump thereby allowing the fluid from the system pump to be used for other work circuits of the system. One such regeneration circuit is disclosed in U.S. Pat. No. 4,028,889.
One of the problems encountered with such regeneration circuit is that some of the components causing regeneration have heretofore been incorporated within the directional control valve while other components are disposed in the return line between the directional control valve and the tank. Locating the regeneration components at such locations drastically reduces the efficiency of the regeneration circuit. For example, the fluid exhausted from the motor must travel the full length of the motor lines between the motor and the directional control valve, pass through the directional control valve in a first direction and then in the reverse direction, and then travel through the full length of other motor lines to the expanding side of the motor. The shape of the passages through the valve body and the flow control element therein restricts fluid flow therethrough thereby generating a pressure drop in the exhausted fluid. An additional pressure drop is generated due to the fluid having to travel through the motor lines which on some vehicles can exceed 7 or 8 meters. The combined effect of the higher pressure drops necessitates the pressure settings of the regeneration circuits to be at a higher level to adequately provide regeneration.
In view of the above, it would be desirable to have a regeneration circuit in which the exhausted fluid bypasses the directional control valve and is located close to the hydraulic motors to minimize the length of the flow path between the contracting and expanding sides of the hydraulic motor. The magnitude of the pressure drop in the exhausted fluid is reduced by bypassing the control valve and shortening the fluid flow path between the retracting and expanding sides of the motors. Minimizing the pressure drop increases the efficiency of filling the expanding side of the motor.
The present invention is directed to overcoming one or more of the problems as set forth above.